Cantillon Brewmaster Jean Van Roy displays a six liter Methuselah of High Density Lambic in a Brussels bomb shelter where it is aging. / Charles D. Cook for USA TODAY

by Charles D. Cook, Special for USA TODAY

by Charles D. Cook, Special for USA TODAY

BRUSSELS - Brasserie Cantillon, the highly regarded Belgian brewer, has come up with an unusual venue for aging its beloved lambics: a bomb shelter.

"The idea to start this project came to me when I visited a Champagne house," brewmaster Jean Van Roy says. "They had great cellars, with bottles aging in beautiful conditions. I wanted to do the same with Cantillon."

There was a problem: Cantillon is running out of space in its circa-1900 brewery near Brussels' Midi train station. "Making lambic beer is a time-consuming process, and we need a lot of space for all of our wooden barrels. So there isn't much room left here in the brewery," Van Roy says. "I contacted the city of Brussels, and they agreed to collaborate,"

A number of possible sites for an aging facility were considered, but one really stood out: an old bomb shelter underneath a park near the Leopold Tunnel in central Brussels. "It's a fine location for a cellar, and there is some family brewing history here," Van Roy says. "My great great grandfather, René Troch, worked with lambic beer nearby. It makes this location very special."

Freddy Thielemans, a former mayor of Brussels, says the cellar "is in the old basin of the river Senne, transformed into cellars at the time of 'vaulting' and the diversion of the water away from Brussels. These cellars were then converted into bomb shelters."

The project is a very sweet deal for Cantillon. "We have a 30-year lease from the city, for free," Van Roy said, grinning. "It's a very good situation."

Why age beer in a cellar? Some brews, such as lambics, can improve with age, even for up to 20 or 30 years. Lambics are tart, funky brews produced by spontaneous fermentation with wild yeasts, then aged in wooden barrels for a few months to several years.

When lambics of different ages are blended together, then bottled with the addition of liquid sugar to spark refermentation, the result is Oude Gueuze. This champagne-like beer, a cult favorite, can be highly effervescent, with a supremely dry tartness that can be shocking to the uninitiated - and absolute nectar for aficionados. Count me among the latter."I do this project, not for me, or for Cantillon, but for lambic itself, to see how these beers will age," Van Roy says.

The environmental conditions in the cellar/bomb shelter are nearly ideal for aging beer, as the temperature ranges around 50 to 60 degrees Fahrenheit for most of the year.

As to which beers will be aged in the cellar, Van Roy says, "At the moment, we have Bruocsella Grand Cru, Oude Gueuze and High Density Lambic here."

The Oude Gueuze is a very special one. "It is a blend of 2-, 3- and 4-year-old lambics averaging 40 months old. So this gueuze is twice as old as our Classic," Van Roy says as we tour the cinderblock and concrete facility.

Cantillon is also known for its numerous fruit lambics. "We will likely put some beers with a high-fruit concentration here," Van Roy says.

There are about 10,000 bottles in the cellar, ranging in size from 750 milliliters to 6-liter behemoths known as Methuselah. Thirty years from now, that number will be in the 60,000 to 80,000 range.

The brewer says he's too busy to give tours of the cellar to the public, but the city of Brussels is considering organizing some events there, and "some people will be able to visit if and when that happens."

Charles D. Cook (higrav1@gmail.com) has visited Belgium 28 times since 1994 to explore, experience and enjoy its incredible beer culture. He writes for various publications, including All About Beer Magazine, Celebrator Beer News and his own website, drinkbelgianbeer.com.